The invention relates to the use of 5-(2,4-Dihydroxy-5-isopropyl-phenyl)-4-(4-morpholin-4-ylmethyl-phenyl)-isoxazole-3-carboxylic acid ethylamide or a pharmaceutically acceptable salt, hydrate or solvate thereof, for the manufacture of pharmaceutical compositions for use in the treatment of cancer of the breast, and to 5-(2,4-Dihydroxy-5-isopropyl-phenyl)-4-(4-morpholin-4-ylmethyl-phenyl)-isoxazole-3-carboxylic acid ethylamide or a pharmaceutically acceptable salt, hydrate or solvate thereof, for use in the treatment of cancer of the breast.

Management of cancer of the breast is a major problem.

Heat shock protein 90 (Hsp90) is recognized as a new anti-cancer target. Hsp90 is a ubiquitous, highly abundant (1-2% of the total cellular protein), essential protein which functions as a molecular chaperone to ensure the conformational stability, shape and function of client proteins. Inhibition of its intrinsic ATPase activity of Hsp90 disrupts the Hsp90-client protein interaction resulting in their degradation via the ubiquitin proteasome pathway. A subset of Hsp90 client proteins, such as Raf, AKT, CDK4 and the EGFR family including ErbB2 are oncogenic signaling molecules critically involved in cell growth, differentiation and apoptosis, processes which are fundamentaly important in cancer cells. The simultaneous degradation of multiple oncoproteins is believed to produce the anti-tumor effects observed with Hsp90 inhibitors.

The Hsp90 family of chaperones is comprised of four members: Hsp90α and Hsp90β both located in the cytosol, GRP94 in the endoplasmic reticulum, and TRAP1 in the mitochondria (Csermely et al., 1998). Hsp90 is the most abundant cellular chaperone, constituting about 1% - 2% of total protein (Jakob and Buchner, 1994). Among the stress proteins, Hsp90 is unique because it is not required for the biogenesis of most polypeptides (Nathan et al., 1997). Its cellular targets, also called client proteins, are conformationally labile signal transducers that play a critical role in growth control, cell survival and tissue development (Pratt and Toft, 2003).

Hsp90 chaperones, which possess a conserved ATP-binding site at their N-terminal domain (Chene, 2002) belong to a small ATPase sub-family known as the DNA Gyrase, Hsp90, Histidine Kinase and MutL (GHKL) sub-family (Dutta and Inouye, 2000). The chaperoning (folding) activity of Hsp90 depends on its ATPase activity which is weak for the isolated enzyme. However, it has been shown that the ATPase activity of Hsp90 is enhanced upon its association with proteins known as co-chaperones (Kamal et al., 2003). Therefore, in vivo, Hsp90 proteins work as subunits of large, dynamic protein complexes. Hsp90 is essential for eukaryotic cell survival and is overexpressed in many tumors.

The use of various Hsp90 inhibitors for the treatment of cancer, has been previously described in US 2007/105862 A1 and WO 2006/113498 A. 5-(2,4-Dihydroxy-5-isopropylphenyl)-4-(4-morpholin-4-ylmethyl-phenyl)-isoxazole-3-carboxylic acid ethylamide is an Hsp90 inhibitor. Its synthesis is described in example 78 of WO 2004/072051 A.

Surprisingly it has now been found that 5-(2,4-Dihydroxy-5-isopropyl-phenyl)-4-(4-morpholin-4-ylmethyl-phenyl)-isoxazole-3-carboxylic acid ethylamide or a pharmaceutically acceptable salt, hydrate or solvate thereof, is useful in the treatment of cancer of the breast.

Accordingly the present invention provides the use of 5-(2,4-Dihydroxy-5-isopropyl-phenyl)-4-(4-morpholin-4-ylmethyl-phenyl)-isoxazole-3-carboxylic acid ethylamide or a pharmaceutically acceptable salt, hydrate or solvate thereof, for the manufacture of pharmaceutical compositions for use in the treatment of cancer of the breast.

In a further aspect the present invention provides 5-(2,4-Dihydroxy-5-isopropyl-phenyl)-4-(4-morpholin-4-ylmethyl-phenyl)-isoxazole-3-carboxylic acid ethylamide or a pharmaceutically acceptable salt, hydrate or solvate thereof, for use in treating cancer of the breast.

In a further aspect the present invention provides a pharmaceutical preparation for the treatment of cancer of the breast comprising 5-(2,4-Dihydroxy-5-isopropyl-phenyl)-4-(4-morpholin-4-ylmethyl-phenyl)-isoxazole-3-carboxylic acid ethylamide or a pharmaceutically acceptable salt, hydrate or solvate thereof, and at least one pharmaceutically acceptable carrier.

Depending on species, age, individual condition, mode of administration, and the clinical picture in question, effective doses for example weekly doses of about 2 to 300 mg, preferably 50 to 160 mg of 5-(2,4-Dihydroxy-5-isopropyl-phenyl)-4-(4-morpholin-4-ylmethyl-phenyl)-isoxazole-3-carboxylic acid ethylamide or a tautomer thereof or a pharmaceutically acceptable salt or a hydrate or a solvate are administered to a human.

Following is a description by way of example only.

Thirty-seven cancer derived cell lines are used (BT474, MDA-MB-361, MDA-MB-453, SKBr3, T47D, MCF7, MDA-MB-231, MDA-MB-468, SK-MEL-5, A375, MALME-3M, SK-MEL-28, WM266.4, RPMI8226, U266, BE, Colo205, HCT116, HT29, MAWI, RKO, U87MG, HN5, RPMI-8226, A549, MV522, NCI-H1299, NCI-H460, 41M, A2780, CH1, NCI-N87, SKOV3, PC3, MO7e, GIST882 and Baf3) to test the effect of 5-(2,4-Dihydroxy-5-isopropyl-phenyl)-4-(4-morpholin-4-ylmethyl-phenyl)-isoxazole-3-carboxylic acid ethylamide. Cell lines are commercially available from American Type Culture Collection (ATCC). These cell lines cover the following 12 cancer or tumor types: breast, melanoma, multiple myeloma (MM), colon, glioblastoma, head & neck, leukemia, lung, ovarian, prostate, stomach and gastrointestinal stromal tumour (GIST). After division and medium change, cells from stock culture are seeded on cell plates and cultured for about 18 hours to allow cell growth and attachment before starting the assay. On the first day of the assay, 5-(2,4-Dihydroxy-5-isopropyl-phenyl)-4-(4-morpholin-4-ylmethyl-phenyl)-isoxazole-3-carboxylic acid ethylamide is added to the medium at various concentrations up to 10 µ. Cells are cultured up to 72 or 96 hours and cell proliferation is determined using commercially available cell proliferation kits.

Table 1 shows the concentrations (nM) of 5-(2,4-Dihydroxy-5-isopropyl-phenyl)-4-(4-morpholin-4-ylmethyl-phenyl)-isoxazole-3-carboxylic acid ethylamide which inhibit cell proliferation by 50% (IC₅₀). The cells were continually exposed to 5-(2,4-Dihydroxy-5-isopropyl-phenyl)-4-(4-morpholin-4-ylmethyl-phenyl)-isoxazole-3-carboxylic acid ethylamide for either 72 or 96 hours and cell growth was determined by commercially available kits based on either SRB, Alamar blue, methylene blue or WST-1 methods. Tumor type Cell line IC₅₀ (nM) Breast BT474 2.8 MDA-MB-361 6 MDA-MB-453 3.9 SKBr3 2.3 T47D 2.6 MCF7 2.3 MDA-MB-231 7.7 MDA-MB-468 3.5 Melanoma SK-MEL-5 3 A375 3 MALME-3M 7.7 SK-MEL-28 8 WM266.4 6.2 Multiple myeloma (MM) RPMI8226 36.7 U266 23.3 Colon BE 2.8 Colo205 6.2 HCT116 16 HT29 30 MAWI 50 RKO 3.1 Glioblastoma U87MG 6 Head & Neck HN5 8 Leukemia RPMI-8226 6.3 Lung A549 11.7 MV522 8.1 NCI-H1299 5.7 NCI-H460 14 Ovarian 41M 3 A2780 6.1 CH1 2.8 SKOV3 3.7 Prostate PC3 5 Stomach NCI-N87 0.2 Gastrointestinal stromal MO7e 10.6 tumour (GIST) GIST882 6.2 Baf3 22.4

Data relating to tumor types other than breast is outside the scope of the claims.

The anticancer activity of 5-(2,4-Dihydroxy-5-isopropyl-phenyl)-4-(4-morpholin-4-ylmethyl-phenyl)-isoxazole-3-carboxylic acid ethylamide is evaluated in 30 human tumor xenografts in vitro using a clonogenic assay. In this assay, human cells derived from cancer patients are evaluated for the capacity of 5-(2,4-Dihydroxy-5-isopropyl-phenyl)-4-(4-morpholin-4-ylmethyl-phenyl)-isoxazole-3-carboxylic acid ethylamide to inhibit the formation of 3 dimensional colonies. These consist of tumor cells that possess the potential for anchorage independent growth in semisolid medium. The tumor xenografts which have never been cultured in cell culture plastic dishes are isolated from nude mice. Tumor cell suspensions are prepared and incubated in 24 well plates containing layers of soft agar. Under these conditions a special subpopulation of cells selectively grows to colonies. 5-(2,4-Dihydroxy-5-isopropyl-phenyl)-4-(4-morpholin-4-ylmethyl-phenyl)-isoxazole-3-carboxylic acid ethylamide was tested in 6 concentrations up to 10 µM. The tumor test panel comprises 1 to 6 models of 10 different human tumor or cancer types, which were bladder cancer, colon, liver, non small cell lung (adeno, squamous epithelium and large cell), small cell lung, mammary, ovary, pancreatic, melanoma and pleuramesothelioma. Antitumor effects are recorded as inhibition of colony formation in relation to untreated controls. The concentration which results in 50% reduction in colony formation (IC₅₀) are shown in Table 2. Further information on the method has been published (Burger et al., 2004; Fiebig et al., 2004; Smith et al., 2005).

Table 2 shows the concentration (nM) of 5-(2,4-Dihydroxy-5-isopropyl-phenyl)-4-(4-morpholin-4-ylmethyl-phenyl)-isoxazole-3-carboxylic acid ethylamide which inhibits colony formation by 50% (IC₅₀). The cells are continually exposed to 5-(2,4-Dihydroxy-5-isopropylphenyl)-4-(4-morpholin-4-ylmethyl-phenyl)-isoxazole-3-carboxylic acid ethylamide and colony formation is determined. Tumor Type Tumor model Histology IC50 (nM) Bladder BXF 1218 Transitional cell carcinoma 27 BXF 1228 Transitional cell carcinoma 630 Colon CXF 1103 Adeno carcinoma 13 CXF 158 Adeno carcinoma 369 CXF 1729 Carcinoma 467 CXF 1784 Carcinoma 418 CXF 609 Adeno carcinoma 55 Liver LIXF 575 Hepatocellular carcinoma 34 Lung, non- small cell LXFA 297 Adeno carcinoma 28 LXFA 526 Adeno carcinoma 5 LXFA 629 Adeno carcinoma 35 LXFA 983 Adeno carcinoma 126 LXFE 1422 Squamous cell carcinoma 48 LXFL 1647 Large cell lung carcinoma 34 Lung, small cell LXFS 615 Small cell lung carcinoma 30 LXFS 650 Small cell lung carcinoma 2 Breast MAXF 1162 Invasive ductal carcinoma 304 MAXF 1322 Pap. adeno carcinoma 29 MAXF 1384 Adeno carcinoma 209 MAXF 401 Pap. adeno carcinoma 78 MAXF 583 Ductual adeno carcinoma 333 Melanoma MEXF 1539 Melanoma 3 MEXF 462 Amelanotic melanoma 24 MEXF 535 Amelanotic melanoma 43 MEXF 672 Amelanotic melanoma 18 MEXF 989 Amelanotic melanoma 2 Ovary OVXF 1353 Adeno carcinoma 26 OVXF 1544 Carcinoma 53 Pancreas PAXF 1657 Adeno carcinoma 39 Pleuramesothelioma PXF 1118 Biphasic pleuramesothelioma 223

Data relating to tumor types other than breast is outside the scope of the claims.

The estrogen receptor positive cell line BT-474 was initially isolated from a human breast ductal carcinoma established from a solid, invasive ductal carcinoma of the breast obtained from a 60-year-old woman (ATCC number HTB-20). The cells are grown in DMEM high glucose (4.5 g/l) supplemented with 10% FCS, 200 mM L-glutamine and 1% sodium pyruvate.

In preparation for cell inoculation, each mouse is subcutaneously implanted on the upper dorsal side with a 17β-Estradiol pellet (25 µg/day; 90 day release) using a trocar needle. BT-474 cells (5x10^6) are injected in 200 µl Matrigel:HBSS (1:1 vol) (BD Matrigel™ Basement Membrane Matrix). The injection site is subcutaneously in the right flank. Treatment with AUY922 is initiated when the average tumor volume reached approximately 100 mm³. Tumor growth is monitored at regular intervals. The xenograft tumor sizes are measured manually with calipers and the tumor volume is estimated using the formula: (W x L x H x π/6), where width (W), height (H) and length (L) are the three largest diameters.

Results are presented as mean ± SEM. Tumor data are analyzed by ANOVA with post hoc Dunnet's test for comparison of treatment versus control group. As a measure of efficacy the %T/C value is calculated at the end of the experiment according to: $$\left(\mathrm{\Delta }{\mathrm{tumor\; volume}}_{\mathrm{treated}}/\mathrm{\Delta }{\mathrm{tumor\; volume}}_{\mathrm{control}}\right)*100$$ where Δtumor volumes represent the mean tumor volume on the evaluation day minus the mean tumor volume at the start of the experiment.

The antitumor effect of AUY922 is evaluated in the BT-474 xenograft model. In this study, the treatment period is 21 days. Each group consists of eight tumor bearing animals. At the end of the study, the tumor sizes in the treatment groups are compared to those of the vehicle treated groups and the effect is expressed as %T/C. Statistically significant reduction of tumor sizes are observed when AUY922 is administered once per week at 17-25 mg/kg (Table 3). Compound Dose, schedule, route T/C (%) ΔTumor volume (mm³) Vehicle control 10 ml/kg, qw, i.v. 100 528 ± 123 AUY922 8.3 mg/kg, qw, i.v. 43 229 ± 73 AUY922 17 mg/kg, qw, i.v. 9 46 ± 27* AUY922 25 mg/kg, qw, i.v. 3 15 ± 23* * P < 0.05; one-way ANOVA post hoc Dunnet's test.

The transplantable rat breast cancer tumor BN472 is serially passaged as fragments in female syngeneic Brown Norway rats. The injection site is orthotopically in the mammary fat pad. Treatment with AUY922 is initiated when the average tumor volume reaches approximately 100 mm³. Tumor growth is monitored at regular intervals. The xenograft tumor sizes are measured manually with calipers and the tumor volume is estimated using the formula: (W x L² x π/6), where width (W) and height (H) are the two largest diameters. Results are presented as mean ± SEM. Tumor data were analyzed by ANOVA with post hoc Dunnet's test for comparison of treatment versus control group. As a measure of efficacy the %T/C value is calculated at the end of the experiment according to: $$\left(\mathrm{\Delta }{\mathrm{tumor\; volume}}_{\mathrm{treated}}/\mathrm{\Delta }{\mathrm{tumor\; volume}}_{\mathrm{control}}\right)*100$$ where Δtumor volumes represent the mean tumor volume on the evaluation day minus the mean tumor volume at the start of the experiment.

The antitumor effect of AUY922 is evaluated in the BN472 xenograft model. Each group consists of seven tumor bearing animals. At the end of the study, the tumor sizes in the treatment groups are compared to those of the vehicle treated groups and the effect is expressed as %T/C. Statistically significant reduction of tumor sizes is observed when AUY922 was administered once per week at 50 mg/kg (Table 4). Compound Dose, schedule, route T/C (%) ΔTumor volume (mm³) Vehicle control 2 ml/kg, qw, i.v. 100 5569 ± 1639 AUY922 25 mg/kg, qw, i.v. 78 4357 ± 1338 AUY922 50 mg/kg, qw, i.v. 21 1148 ± 152* * P < 0.05; one-way ANOVA post hoc Dunnet's test.

The transplantable rat pancreatic tumor CA20948 is serially passaged as cell homogenates in male syngeneic Lewis rats. The injection site is subcutaneously on the right flank. Treatment with AUY922 is initiated when the average tumor volume reaches approximately 100 mm³. Tumor growth is monitored at regular intervals. The xenograft tumor sizes is measured manually with calipers and the tumor volume is estimated using the formula: (W x L² x π/6), where width (W) and height (H) are the two largest diameters.

Results are presented as mean ± SEM. Tumor data were analyzed by ANOVA with post hoc Dunnet's test for comparison of treatment versus control group. As a measure of efficacy the %T/C value is calculated at the end of the experiment according to: $$\left(\mathrm{\Delta }{\mathrm{tumor\; volume}}_{\mathrm{treated}}/\mathrm{\Delta }{\mathrm{tumor\; volume}}_{\mathrm{control}}\right)*100$$ where Δtumor volumes represent the mean tumor volume on the evaluation day minus the mean tumor volume at the start of the experiment.

The antitumor effect of AUY922 is evaluated in the CA20948 xenograft model. Each group consisted of six tumor bearing animals. At the end of the study, the tumor sizes in the treatment groups are compared to those of the vehicle treated groups and the effect is expressed as %T/C. Statistically significant reduction of tumor sizes is observed when AUY922 is administered once per week at 50 and 75 mg/kg (Table 5). Compound Dose, schedule, route T/C (%) ΔTumor volume (mm³) Vehicle control 2 ml/kg, qw, i.v. 100 23267 ± 7810 AUY922 50 mg/kg, qw, i.v. 30 7090 ± 2553* AUY922 75 mg/kg, qw, i.v 21 4796 ± 1354* * P < 0.05; one-way ANOVA post hoc Dunnet's test.

Example 5 is outside the scope of the claims.